The "Did you know" thread.....

[Roubignol]

There are four basic types of tissue found in the human body. These are subdivided into different subtypes, for example, blood and bone are both connective tissues. Each type has different properties—such as strength, flexibility, or movement—that makes it suited to a specific task.

These tissues are:

Connective tissue
Connects, supports, binds, and separates other tissues and organs.

Epithelial tissue
Closely packed cells in one or more layers that form barriers.

Muscle tissue
Long, thin cells that relax and contract to create movement.

Nervous tissue
Cells that work together to transmit electrical impulses.

Your body is made up of approximately 10 trillion cells , and each one is a self-contained, living unit.

One trillion means 1 billion of 1 billion.
Yep... thaaatt's a lot.

Most cells have a diameter of only 0.001 mm

[Numerous One]

Originally Posted by xyzde69

Your body is made up of approximately 10 trillion cells

And every (EVERY) cell in our body is replaced with a new one within a period of ten years. That means that after 10 years we literally are not the same person any more (on a physiological level; mentally, I see no radical progressive motion from me as a teenager ).

[Roubignol]

Originally Posted by Numerous One

And every (EVERY) cell in our body is replaced with a new one within a period of ten years. That means that after 10 years we literally are not the same person any more (on a physiological level; mentally, I see no radical progressive motion from me as a teenager ).

I didn't reach this chapter.
Even cells of bones and cartilages?

[Numerous One]

Originally Posted by xyzde69

I didn't reach this chapter.
Even cells of bones and cartilages?

Well, that's roughly rounded, because it sounds neat, and I wanted to sound smart.

Different tissues in the body replace cells at different rates. Naturally, that doesn't count for neurons in cerebral cortex at all. There are no neurons added to a cerebral cortex after birth. Any cerebral cortex neurons that die are not replaced (that's a "minor" fuckery alcohol sessions impose on us).

The confusing part about the data given in researches is that our brains, obviously, grow bigger after birth. So where is all the extra bulk coming from? In the brain, no cerebral cortex neurons are added, but research hasn’t been completed on other parts of the brain, and even if it were to turn out that no other neurons are added, lots of other kinds of cells are added. Glial cells, for example, may actually make up 90% of the cells in the brain. It used to be thought that glial cells were simply the scaffolding of the brain, with no real role in the processing of the brain. In recent years, however, it has become clear that glial cells play key roles in processing.

Red blood cells live for about four months, while white blood cells live on average more than a year. Skin cells live about two or three weeks. Sperm cells have a life span of only about three days. Colon cells have it rough: they die off after about four days (but considering their job and lousy conditions they have to perform in, it's not much of a waste, and it's not their biggest issue).

So, yes, it's roughly rounded.

[ManofKent]

Originally Posted by Numerous One

And every (EVERY) cell in our body is replaced with a new one within a period of ten years. That means that after 10 years we literally are not the same person any more (on a physiological level; mentally, I see no radical progressive motion from me as a teenager ).

What about BRAIN cells? How does that work with them?

Brain cells store memory engrams etc. If they are replaced with brand new ones every decade why don't we keep forgetting EVERYTHING we know?

[rosestone]

Originally Posted by ManofKent

What about BRAIN cells? How does that work with them?

Brain cells store memory engrams etc. If they are replaced with brand new ones every decade why don't we keep forgetting EVERYTHING we know?

Why do we look (more or less) the same, when all the cells have changed? Why is our nose the same shape as it was? Why don't scars disappear? Where do 'I' live in my body? What is "me", am I in fact a completely different being than I was ten years ago? It's all very interesting.

[Numerous One]

Originally Posted by ManofKent

What about BRAIN cells? How does that work with them?

Brain cells store memory engrams etc. If they are replaced with brand new ones every decade why don't we keep forgetting EVERYTHING we know?

I stand corrected, after I got slapped by xyzde69 immediately after my post. That's a many times repeated exaggeration (I wanted to say "myth", but that would connote a pejorative meaning of the term "myth" and derogate it; myths have more layers and convey more meaning, they are too complex to be simply disdained as simple and untrue tales of simple people). But as I said: it sounds neat, and I wanted to sound smart.

I addressed it in the post right after my original half-cocked statement.

Originally Posted by Numerous One

Different tissues in the body replace cells at different rates. Naturally, that doesn't count for neurons in cerebral cortex at all. There are no neurons added to a cerebral cortex after birth. Any cerebral cortex neurons that die are not replaced. [...]

Similar is the situation with cartilage and tendons, which is another question xyzde69 raised. Main cells of those tissues are chondrocytes and tenocytes. While there is theoretically a possibility of chondrocytes regeneration, and it has been demonstrated, alas, in laboratory, in the body the cartilage tissue can not regenerate.

Tenocytes and chondrocytes form from mature stem cells, more specifically Mesenchymal stem cells. These cells can replicate through mitosis, and are present in the body in different tissues like bone marrow. These cells are the key in the regeneration of diverse tissues.

But... there isn't any blood flow to either tendons or cartilage as an adult, so the pathway for migration doesn't exist. And blood flow is the most common (for most of the cells) route for migration. There is another route (neurons do it that way, for an example): cells can migrate using the extracellular matrix as a guide. There's the rub: compared to other connective tissues, cartilage has a very slow turnover of its extracellular matrix and does not repair.
So, yes, cartilage does not repair, and that's the reason for osteoarthritis, for an example, and the pain poor souls affected by it have to live with.

Now, this is not at all my turf. I am mostly autodidact regarding human anatomy and physiology, after that basic knowledge I've acquired during my primary and high school education. Simply because of my interests, and it is handy when you look at a nude photo of your favourite pornstar on VEF . So, I am pleading VEF fellows with more credentials in this field to correct me if anything I've just said was incorrect.

[Numerous One]

Originally Posted by rosestone

Why do we look (more or less) the same, when all the cells have changed? Why is our nose the same shape as it was? Why don't scars disappear? Where do 'I' live in my body? What is "me", am I in fact a completely different being than I was ten years ago? It's all very interesting.

We don't look the same. We grow old. I remember I've read an interesting analogy between the cell replicating process and photocopying process. Next generation of cell contains a little bit of error, then the next... the errors accumulate, thus we get wrinkled. Add the free radicals, other bad environmental influences, etc. That, again, sounds interesting to a layman like me, but again, it's not my turf.

But I understand what you wanted to say. The cells replicate. That is, all the information in a cell is passed to a successor. That way everything, from the cell dimensions to it's position in the structure is passed. That's why our snout shape is destined to be the same old one.

Now the more interesting part, by an order of magnitude greater (for me, at least) of rosestone's post is about "I".

The identity and consciousness could never be explained on a material, exclusively physiological ground. This is the point at which "science" today (if we judge of it by the path it has taken some 150 years ago) shows up as a dogmatic, closed system of doctrines. Where is "I" contained, in which organ? Would it be brain? And could that really be a complete answer? If a person looses his/her arm, would he/she feel less of the "self". Or another arm, and then a leg... At which point, and with which part of the body would "self" perish? I know it may sound simplified, but, really, those are all legitimate human questions.

Mechanistic interpretation would never be sufficient in explaining the entirety of human being. "I" is more than a sum of it's parts.

But that's way too complicated subject to be discussed in VEF posts.

[Greenman]

Bruce Forsyth's Generation Game catchphrases and sayings:

"Ladies, gentlemen and children welcome to the Generation Game, it's nice to see you, to see you...NICE!"

"Let's meet the eight, who are going to generate"

"Didn't he/she do well!"

"What's on the board Miss Ford?" (Rosemary Ford the new girl helper in the 90's)

"Anthea give us a twirl!" (Anthea Redfern, the first girl helper who was a former Playboy bunny and would later be the second Mrs Forsyth) when she came on in a really beautiful frock or gown.

"Good game, good game"

"Oh I'll make a note of that..."(Bruce would write on the contestant's card something amusing)

"Let's have a look at the old scoreboard"

"You have 45 seconds to recount your thoughts...starting now!" Contestants had to remember all the goods that went past them on a moving conveyor belt)

"We're sorry to lose you!" (When contestants unfortunately don't have enough points to go through to the next round or the final)

"On behalf of everyone and I mean everyone, thank you for watching and see you next week...BE THERE!"

[WURZ]

HAPPY MEMORIES GREENMAN......................